1. Field of the Invention
The present invention relates to vibration and mechanical shock protection of electronic devices. More specifically, the present invention relates to the fluid damping structures for the protection of hard disk drives and other sensitive electronic devices used in high vibration and shock environments.
2. Description of the Related Art
The increasing popularity and computing performance of portable electronic devices such as cell phones, MP3 players, global positioning units, PDAs and portable computers, coupled with the miniaturization and increased storage density of hard disk drives, has migrated demand for the hard disk drive into these portable devices. However, the hard disk drive was never designed to be used in high vibration or high impact and shock environments. Redesigning the hard drives to meet such requirements would increase costs and reduce demand for many portable, cost sensitive applications such as cell phones and MP3 players. It would be useful to have a packaging system that would isolate currently designed drives from shock and vibration to enable such drives to be used in portable devices.
U.S. Pat. Nos. 6,243,228; 6,583,950; 6,697,218; and Patent Application Publications US 2002/0030922, US 2003/0174436, to Yoshida et al., disclose shock-absorbing materials made from a mixture of solid particles and viscous elastic material is arranged at the periphery of an information storage and retrieval device. When an external shock is applied to the device, the shock-absorbing material is greatly deformed and dissipates the shock energy by inner friction sufficiently to prevent damage to the inner mechanism of the device. The deformed shock-absorbing material can be restored to the original shape so that it is repeatedly usable. However, the shock absorbing material disclosed in the aforementioned references requires that the storage device be manually repositioned to its original position after impact. This is impractical in most potable device applications because users usually do not open their cell phones or MP3 players after they are shocked or dropped, due to the difficulty of opening such miniature devices. Often, the manufacturer discourages such action by voiding warranties. The shock absorbing materials are complex solids containing a wide variety of components including sand, springs, complex webs, and cloth contained within a solid viscous elastic material. These materials may be expensive to manufacture, increasing the potential cost of the hard drives and reducing the desirability for their use in mass produced portable applications. Additionally, it is unclear as to whether the disclosed structures are effective for isolating vibration which may be just as destructive to the hard drive if present over prolonged period of time.
US Patent Application Publication 2004/0070867 discloses cushioning devices placed at the four corners of the hard disk drive to suspend the drive within an external frame. The cushioning devices are composed of various types or rubber or solid viscous elastic material such as silicone gels. However, the area supported by the cushioning devices is limited, which may create compromises between shock protection and vibration isolation. That is, to protect effectively against shock loads with cushioning devices having a small contact area, requires stiffer material that may transmit more vibration.
What is needed is a low cost, simple method to effectively provide shock and vibration protection to hard disk drives and other sensitive electronic devices.